Yeah, it's not clear. But the great thing with this cheap stuff is even if it doesn't work, you still have a PCB and some parts to play with. I think you just buy it and play with it.
Function 4:
Timing and then pull off: After power, immediately pull the relay, the relay off delay time T1 after arrival; T2 arrive after disconnecting time relay, -270 hour in 0.1 seconds delay time between T1 and T2 adjustable to CH1 interface a low pulse signal, repeat the above functions;
Apply power, I guess the NO contact closes for delay time, then it opens and stays open.
Half the fun with this stuff is translating the english.